posted on 2023-03-22, 22:14authored byBenjamin
W. McDowell, Jon M. Mills, Motoaki Honda, George V. Nazin
Alkali halides are well-known for
their tendency to form rock-salt-like
crystal structures. Here we present a scanning tunneling microscopy
study of a previously unreported alternative structure of one such
alkali halide, RbI. When deposited on Ag(111) at a low submonolayer
surface coverage, RbI forms islands with hexagonally coordinated atomic
structures, in contrast to the expected rock-salt structures typically
observed for such alkali halide films on metal surfaces. At a near-monolayer
RbI surface coverage, we observe the coexistence of the hexagonally
coordinated phase and a square-coordinated rock-salt-like RbI phase
that is analogous to that observed for other alkali halides. Our density
functional theory calculations for this system highlight the role
of RbI–Ag interfacial charge transfer in defining the RbI structure
and the impact of local atomic coordination on the RbI–Ag charge-transfer
interaction.